Ultraviolet absorbing compounds with a benzotriazole skeleton have conventionally been used as blending agents in medical preparations and cosmetics, or as additives to plastics. These compounds however all have poor dispersibility and solubility in substrates, and as there was a limit to their blending proportion and stability in dispersion, they suffered from bleeding and other disadvantages.
Further, although silicone oils find application in a variety of different fields, benzotriazole type compounds suffered from the disadvantage of being difficulty soluble in silicone oils.
To remedy these disadvantages, alkoxysilyl groups may for example be introduced into the benzotriazole skeleton, and the benzotriazole skeleton then introduced into polysiloxane molecules by cohydrolysis with chlorosilanes or alkoxysilanes (Unexamined Published Japanese Patent Application No. 57-21391).
When this method was applied to polysiloxanes without reactive functional groups, however, the benzotriazole type compound tended to be hydrolyzed due to the presence of the alkoxysilyl groups, and it lacked stability. In particular when these hydrolyzable substances were used for medical or cosmetic applications, moreover, the hydrolysis products had an irritating effect on the skin and membranes.
Another method has been proposed whereby the phenolic hydroxyl groups of compounds with a benzotriazole skeleton have been utilized to make alkyl ether derivatives with vinylsilyl groups, and hydrosilylation carried out on these vinyl groups so as to introduce benzotriazole type compounds into polysiloxane molecules (Unexamined Published Japanese Patent Application No. 63-230681).
In the case of compounds with this alkyl phenyl ether skeleton, however, radical cleavage via quinone intermediates tended to occur when ultraviolet radiation was absorbed or showed a tendency to hydrolysis under acidic conditions, and stability was poorer than in the case of alkylation via carbon-carbon bonds.
As described above, despite the fact that the use of silicone oils has been increasing in recent years in the medical and cosmetic fields, compounds which are alkyl modified via carbon-carbon bonding with a benzotriazole compound so as to introduce the benzotriazole skeleton into a polysiloxane molecule, or compounds which do not have hydrolyzable alkoxysilyl groups, which are stable and yet are highly soluble in silicone oils, had still not been obtained.